Cadmium Telluride (CdTe) is one of the most well established II-VI compounds largely due to its use as a photonic material. Existing applications, as well as those under consideration, are increasingly demanding stringent control of the material properties. The deposition of high quality thin films is of the utmost importance to such applications. This tendency has also manifested itself in the structural and surface morphology with higher structural perfection yielding smoother surfaces. The present investigations are about the structural and surface characterization of CdTe thin films. Thin films of CdTe with thickness around 4000Å have been deposited by the thermal evaporation method at room temperature. The structural characterization of this film was carried out using XRD (X-ray diffraction technique) and TEM (Transmission electron microscopy). The structure of CdTe film was found to be hexagonal. Also, the lattice parameters, grain size (D), dislocation density (ρ) and micro strain (ε), were taken from the XRD data. From TEM of CdTe thin films, the polycrystalline nature was confirmed. A surface morphology study was done by SEM (Scanning electron microscopy) technique. Atomic Force Microscopy (AFM) provides numerical data of surface height at digitized locations, which are usable for various surface characterizations. In this paper, the results have been analyzed to draw some conclusions which are also presented here.

WSe2 is a member of groupVI Transition Metal Dichalcogenides (TMDCs) and has been observed to be a highly stable semiconducting material. It has been grown in crystal form using a direct vapour transport technique in present case. The grown WSe2 crystals were characterized for the structural properties using X-ray diffraction technique (XRD). The hexagonal structure was confirmed through this analysis. Using the data of XRD, various parameters like crystalline size, lattice parameters, micro strain, dislocation density, unit cell volume, unit cell density, growth fault and deformation fault probability etc were found. It was seen that the micro strain, dislocation density and growth & deformation fault probabilities were found to be very low in WSe2 crystals. The grown WSe2 crystals were characterized for optical properties using UV-VIS-NIR spectroscopy. The absorption spectra of WSe2 grown in present case revealed the fact that WSe2 posses direct band gap around 1.38eV. Layered di-chalcogenides WSe2 (or MoSe2) are used for desired applications such as in photo-conversion devices.

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Group II-VI compounds have been investigated largely in last two decades due to their interesting optoelectronic properties. ZnTe, a member of this family, possesses a bandgap around 2.26eV. This material is now a day investigated in thin film form due to its potential towards various viable applications. In this paper, the authors report their investigations on the preparation of ZnTe thin films using vacuum evaporation technique and their structural and optical characterizations. The structural characterization, carried out using an X-ray diffraction (XRD) technique shows that ZnTe used in present case possesses a cubic structure. Using the same data, the micro strain and dislocation density were evaluated and found to be around 1.465×10-3lines-m2and 1.639×1015lines/m2respecctively. The optical characterization carried out in UV-VIS-NIR region reveals the fact that band gap of ZnTe is around 2.2eV in present case. In addition to this, it was observed that the value of bandgap decreases as the thickness of films increases. The direct transitions of the carries are involved in ZnTe. Using the data of UV-VIS-NIR spectroscopy, the transmission coefficient and extinction coefficient were also calculated for ZnTe thin films. Besides, the variation of extinction coefficient with wavelength has also been discussed here.

Cadmium sulphide (CdS), a member of group II-VI semiconductors, is a promising material based on its applications. The present investigations describe the preparation and electrical characterization of CdS thin films. CdS thin films with thickness of 1000 nm were deposited by vacuum evaporation at room temperature. Characteristic parameters of Schottky junctions formed by a thermal vapor deposition of 500 nm of Al films on pre-coated CdS glass substrates were obtained experimentally from the I-V characteristics in the temperature range of 303-393 K. Diode parameters, such as the zero-bias barrier height φ b0 , flat band barrier height Φ bf , ideality factor η, and series resistance R S were investigated using the thermionic emission method.